This course follows the Introduction to General Relativity with derivation of Einstein's equation from fundamental action principles, and the study of the application of General Relativity to Astrophysics and Cosmology. We begin by outlining how Einstein's equations can be derived from an action principle from scratch, then discuss possible alternative theories of gravity and extra dimensions. We then discuss the production and detection of gravitational waves as a probe of astrophysical and cosmological phenomena. Next, we develop the story of homogeneous isotropic FRW cosmology, and introduce the idea of inflation. Then we discuss aspects of the thermal physics of the early universe. After that, we give an outline of the theory of inflationary perturbations, how they grow over time, and how this can be read off the cosmic microwave background and directly dictates the formation of large scale structure in our universe today.